Preconditioning a Tesla battery should be done when the battery has been idle and unused for longer than 10 days.
To precondition your Tesla battery, start by connecting the charger and plugging it into the car. Turn on the car, and the charge port will light up. Push the button on the charger and the car will begin to charge. Monitor the charge and when it gets to 90%, unplug the cord. Then disconnect the charger and disconnect the car.
When the car is off and unplugged, you should wait for about two hours for the battery to finish preconditioning. Then, turn the car back on, plug the charger back in, and begin charging the battery. Continue to monitor the charge until it reaches 90%.
Once full, you will want to unplug the cord from the car and the charger and wait for the car to decrease its charge to 85%, before charging again. This will help keep the battery healthy and in shape for optimal range.
Following this process should help ensure that you get the most range out of your Tesla battery.